Re: [PATCH v4 29/35] mm: slub: Move flush_cpu_slab() invocations __free_slab() invocations out of IRQ context

On 8/10/21 4:33 PM, Vlastimil Babka wrote:

On 8/9/21 3:41 PM, Qian Cai wrote:

quoted

quoted

 static void flush_all(struct kmem_cache *s)
 {
-	on_each_cpu_cond(has_cpu_slab, flush_cpu_slab, s, 1);
+	struct slub_flush_work *sfw;
+	unsigned int cpu;
+
+	mutex_lock(&flush_lock);

Vlastimil, taking the lock here could trigger a warning during memory offline/online due to the locking order:

slab_mutex -> flush_lock

Here's the full fixup, also incorporating Mike's fix. Thanks.

One more fixup, sorry for the churn.
----8<----
From 7cfe3fb1bcd6e589199b10bef480ed097ba9de14 Mon Sep 17 00:00:00 2001
From: Vlastimil Babka <redacted>
Date: Wed, 11 Aug 2021 10:51:14 +0200
Subject: [PATCH] mm, slub: fix memory and cpu hotplug related lock ordering
 issues - fix

Make __kmem_cache_do_shrink static to silence "no previous prototype" warning.

Reported-by: kernel test robot <redacted>
Signed-off-by: Vlastimil Babka <redacted>
---
 mm/slub.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/slub.c b/mm/slub.c
index 152487f84025..c9531e03addd 100644
--- a/mm/slub.c
+++ b/mm/slub.c

@@ -4393,7 +4393,7 @@ EXPORT_SYMBOL(kfree);
  * being allocated from last increasing the chance that the last objects
  * are freed in them.
  */
-int __kmem_cache_do_shrink(struct kmem_cache *s)
+static int __kmem_cache_do_shrink(struct kmem_cache *s)
 {
 	int node;
 	int i;

-- 
2.32.0